I have always been fairly balanced in what I keep, but my wife is a different story. She has a tendency to be a bit of a pack rat. Her issue seems to be a mix of both your habits, a little of the nostalgia bug, a little bit of the "I might need this someday" justification. Drives me a bit insane because in both cases she saves way too many things, making our apartment very busy. But hey, what are you going to do? For better or for worse.
We did see Guardians this past Saturday. I liked it quite a bit. I thought the dialog was way better than most of the campy or soulless crap that usually gets scripted for comic book movies these days. I do tend to agree with eLzar about the stinger. It was okay, but not a big deal for me.